Newbie Questions - sequential led lights

[Hsnopi]

Hello All,
So I want to make led lights flash in sequence and go back and forth. Think Kitt on Night Rider or, really, Cylons. I know there are kits to do that but I'd rather learn. I guess my first question is "Is there a better way to refer to this kind of circuit than Flashy Sequential Led Lights Thingy?"?

I think I need to use capacitors somehow. I think I will need to be able to build it from scratch in order to make it fit in the model.
Plus: Nerding Out.

The end state, for those curious, is to add this type of lighting to a Warhammer 40 Doom Scythe. It is simply my motivation.

THanks!

 

[Harald Kapp]

I think "knight rider" is the best fitting search term. "Running lights" or "LED chaser" will also produce many results.

Capacitors alone will not do the job. You'll need transistors, too. There are many ways to build such a circuit. Here's a collection of several such circuits. The hard part is the back and forth movement of the lights. I know of no circuit that does this with a handful of transistors and passive components only (the ones I have seen are running the lights in one direction only).
The "easy" way is using a microcontroller, a handful of LEDs and a piece of software. Your wish to "rather learn" can be granted: use e.g. an arduino (mini) and learn how to code the light sequence.

I had this same project in mind a few years ago. I went this route: Bought an Atmel based kit with PCB to minimize the build effort. Then downloaded the software for the knight rider lights and verified the build. Then the fun part: modifying the software to fit my expectations. For example:
- trying various speed options
- adding a trailing light effect (LEDs not simply on/off, but slowly dimming from on to off using pwm)
- experimenting with different colors.
As I worked from a known good board I knew any malfunction was due to my own programming errors and I knew where to look for them. Today I wouldn't buy a dedicated kit but use, as mentioned above, an Arduino mini for greater flexibility. Also support for the Arduino boards by a large community is ubiquitous (can be found on this forum, too , although we are not explicitly dedicated to such stuff).

 

[bertus]

Hello,

You might want to have a look at this project at AAC:
https://forum.allaboutcircuits.com/threads/project-knight-rider-style-sweeping-light.26977/

Bertus

 

[Audioguru]

A CD4017 is a forwards sequencing counter that is made to go back with diodes. It has a fairly low output current needing transistors at each output to boost the currents. I used a 74HC4017 sequencer that has so much output current that it needs current-limiting resistors. I clock it with a Cmos 555. I made another with the low current CD4017 but added resistors and capacitors and driving transistors for a comet-trails effect.

 

[Hsnopi]

ok, i have a lot to look into here.
For reference, this is the model I am going to adapt it to.

 

[Audioguru]

Are the green lights LEDs or old fashioned light bulbs?
A 4017 has 10 outputs for LEDs but a second one can be added for more outputs.
Will you power the lights with a battery or with an AC-DC power supply?

 

[ratstar]

This circuit works, but it has to run on ac, not dc, oscillator not included. then you dont need a microcontroller. (look mum no microcontroller. )

 

[Hsnopi]

Are the green lights LEDs or old fashioned light bulbs?
A 4017 has 10 outputs for LEDs but a second one can be added for more outputs.
Will you power the lights with a battery or with an AC-DC power supply?

actually, that is really talented airbrush painting. NOT mine. I wish I was that good.

 

[Hsnopi]

so that model is hollow. I need it to run on one of those flat batteries.

 

[Harald Kapp]

I need it to run on one of those flat batteries.

?? Please be more specific. Type, voltage, ...

 

[Audioguru]

A flat battery is a dead one or a Li-PO one. My radio controlled model airplanes use two-cell 7.4V to 8.4V Li-PO rechargeable batteries.
Very small model airplanes and small drones use a very small and flat single cell 3.7V to 4.2V Li-PO battery that cannot light a modern very bright green, blue or white LED. It lights red LEDs fine.